Top Down Unfurled

Written by Peter Dowdney

Originally published December 2019 on mysailing.com

In the coming days, an impressive fleet of over 170 boats will be tackling the unpredictable and often challenging conditions that will be thrown their way as they head south in this year’s Sydney to Hobart yacht race.  This is the 75th anniversary of this iconic sailing event and it has attracted a fleet that ranges from the fully professional race teams of the Super Maxis, right down to the Corinthian crews that will be made up of family members, average club sailors and friends. Some will be taking on the race to win, while others will simply be happy to participate and experience the thrill of crossing the finish line in Hobart. 

While it is too early to predict exactly what weather is going to confront this year’s competitors, there is no question that they will all be much better prepared to face whatever challenges come their way than the generations of sailors that have gone before them. Technological advances in the construction and design of the boats, sails, electronics, hardware, safety equipment and just about every other aspect of modern ocean racing have contributed to making this race a faster, safer and more enjoyable experience for all competitors.

One of the best advances in recent times from the perspective of the sailor is the development of significantly better furling systems for downwind sails. This technology owes its origins to the realms of the Supermaxis and short-handed sailing boats such the IMOCA 60’s, but it has now trickled down into mainstream sailing to the point where most of the competitors in this year’s race will be utilizing the benefits of furling downwind sails in one form or another.    

While the concept of furling a headsail is nothing new, the evolution of “top down furling” has revolutionized the art of handling asymmetrical spinnakers and gennakers on the modern ocean racing yachts.  In the past, the task of dropping a highly loaded asymmetrical sail at night in a heavy seaway, often with a lot of water cascading down the foredeck, was always a risky and challenging “all-hands on deck” maneuver.

These days, the same task can be managed in a matter of seconds with minimal crew involvement and virtually no requirement for them to leave the relative safety of the cockpit or make dramatic adjustments in the course being sailed.

The main differences between a conventional “bottom up” furling systems that are used for sails like Code Zeros, screechers and staysails, and the new form of “top-down” furling for soft asymmetrical sails is firstly in how the sails are attached to the furling hardware, and secondly in the direction in which the sails furl. 

In conventional furling, the sails are attached directly to both the furler unit at the bottom, and the head swivel at the top.  The structure in the luff of these sails is enough to make the sail turn or roll around itself whenever the furler is active. Due to the sail being directly connected to the furler at the bottom, the sail begins to furl in an upwards motion, as soon as the furler starts to turn. 

With top down furling systems, the head of the spinnaker is lashed directly to the top swivel but the tack of the sail flies independently from the furler unit at the bottom. The spinnaker tack is attached to a short strop that is connected to a swivel which allows the furler unit to rotate without pulling in the bottom of the spinnaker. The torsion cable then simply transfers the drive from the furler to the top swivel and this makes the top of the sail start to furl. As the sail continues to furl, it descends from the head, wrapping tightly around the torsion cable as it goes. This makes for a very tight furl and eliminates the risk of having excess material from the asymmetrical sail’s broad shoulders bagging up unevenly. This bagging can cause the sail to catch a gust of wind and unfurl the sail accidentally at a time when you least want it to unfurl.

The tightness and consistency of a well-performed “top-down” furl is what makes this system so good. It significantly reduces the risks associated with hoisting and dropping spinnakers because you simply raise the sail in the air, firm up the torsion cable to the correct tension and unfurl the sail when you are ready. If things get hairy at any point, you can simply furl the sail up and wait for things to be brought back under control. The knowledge that you can get rid of the sail quickly and safely at any time gives the entire crew a lot of confidence and peace of mind.

For further details about top down furling or what you will need to do to convert your boat and sails to adopt this system, check out the furler section of our website at www.ronstan.com.au/marine or talk to your local sailmaker.